Spores are usually the source of the contamination issues, if all the other steps are done right. There are a few vendors I’ve heard of with consistently clean spore syringes, Spore works is one of them.
But going with spores to grains is usually not advised. PF tek with the BRF cakes, like those you wanted to order, is the apparently the way to go for cost (if not using agar). But make them yourself.
The big downside of rice bags is you can’t see the progress or if it’s contamination.